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IBM PS2 Model 80 Technical Reference (April 1987)

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The IBM Personal System/2 Model 80 Technical Reference, April 1987, is IBM's 612-page standalone technical reference for the PS/2 Model 80 (8580). It is written in the pre-1988 format: everything the developer or engineer needed is in one book, including the power supply, the keyboard, the instruction sets and the compatibility notes. From May 1988 onwards IBM moved that common material into the Hardware Interface Technical Reference volumes and the model books shrank to about 90 pages, so this edition contains material that is in no other Model 80 technical reference.

What it contains

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  • Section 1, System Description — the system, its features and specifications.
  • Section 2, Micro Channel Architecture — the full channel description, kept in this book rather than a separate volume.
  • Section 3, System Board and Section 4, System Board I/O Controllers.
  • Section 5, Power Supply (5-1) — description, inputs and input protection, ground leakage current, outputs and output protection, voltage sequencing, no-load operation, auto restart, the power good signal, and the power supply connector pin assignments.
  • Section 6, Keyboard — fourteen national keyboard layouts, the power-on routine and basic assurance test, commands in both directions, and the full Set 1, Set 2 and Set 3 scan code tables.
  • Section 7, Instruction Sets; Section 8, Characters and Keystrokes; Section 9, Compatibility.

What it does not contain

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No FRU part numbers, no removal and replacement procedures and no symptom-to-FRU index — those are in the Hardware Maintenance Reference and Hardware Maintenance Service pamphlets. No schematics and no component values; the planar appears as block diagrams and connector tables. For a Model 80 drawing with component designators on it, see IBM PS2 Model 80 Schematics, which is a third-party set, not IBM's.

What it settles

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This is the primary source for the Model 80 power supply, and it settles several things the wiki previously had to take on trust:

  • Three DC outputs only: +5, +12 and −12 Vdc. There is no −5 V rail on the Model 80.
  • Input 100–125 Vac (range 90–137 Vac) at 5 A nominal, or 200–240 Vac (range 180–265 Vac) at 3 A, 50–60 Hz ±3 Hz, protected by an internal fuse. System unit ground leakage does not exceed 500 µA.
  • Minimum sense levels — +5 V at +4.5 V, +12 V at +10.8 V, −12 V at −10.2 V.
  • Protection — a short between any two outputs or to return latches all outputs off; an internal overvoltage latches them off before any output exceeds 130 % of nominal; the supply restarts only after the fault is cleared and the switch has been off for at least one second (the later desktop supplies specify ten). Outputs track within 50 ms at power-on. The supply will run with no load, at ±25 % regulation, with 'power good' in either state, and it auto-restarts after a mains outage.
  • Power good sources 100 µA and sinks 1 mA, comes up 100–500 ms after +5 V reaches its sense level, and stays active for at least 10 ms after mains is removed.
  • The 15-pin system board power connector pinout — pins 1, 4, 7, 10 and 13 +5 Vdc; pins 2, 5, 6, 8, 11 and 14 signal ground; pin 3 +12 Vdc; pin 9 −12 Vdc; pin 12 Power Good; pin 15 System Status (the line that drives the fixed-disk activity LED, controlled by bits 6 and 7 of System Control Port A, hex 0092). Two 4-pin connectors feed the fixed disk positions.

Download it here: IBM PS2 Model 80 Technical Reference Apr87.pdf

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